In recent years, there has been a demand for a thinner and higher-resolution camera module mounted on cellular phones and the like. In order to meet the thinner and higher-resolution camera modules, refinement of the pixels in an image sensor has progressed. In the image sensor, the smaller the pixel area is, the smaller the light amount entering the pixel is, so that the signal amount is reduced and the signal to noise ratio (SNR) is thus degenerated. Therefore, for the image sensor, it has been desired to achieve the higher sensitivity by the improved efficiency in optical utilization.